This invention relates to an infrared and ultraviolet radiation absorbing glass. The glass has a bronze color and sufficiently high transmittance for visible light and is particularly suitable for use in building and vehicle windows.
For windows of buildings, automobiles and other vehicles there is an increasing demand for sheet glass that is sufficiently transparent to visible light and absorptive of not only infrared rays but also ultraviolet rays.
It is known to render a soda-lime-silica glass absorptive of infrared and ultraviolet rays by incorporating iron in the glass. Ferrous iron expressed as FeO provides the glass with the absorption of infrared radiation, whereas ferric iron expressed as Fe.sub.2 O.sub.3 provides the glass with the absorption of ultraviolet radiation. In practice Fe.sub.2 O.sub.3 is used as the source of the entire iron, and an adequate portion of Fe.sub.2 O.sub.3 is reduced to FeO during the glassmaking process.
Also it is known to incorporate CeO.sub.2 and/or TiO.sub.2 in a soda-lime-silica glass for the absorption of ultraviolet radiation.
From an industrial point of view, it is desired that an infrared and ultraviolet absorbing glass in the form of sheet glass can be produced without significantly changing the conditions of conventional glass melting and refining operations. Also it is desired that an infrared and ultraviolet absorbing glass sheet can easily be toughened by a conventional tempering method. Besides, an infrared and ultraviolet absorbing glass sheet is desired to have a pleasing tint such as bronzy tint.
JP-A-52-102310 shows a neutral grayish- or bronze-colored infrared absorbing soda-lime-silica glass containing as essential components, on a weight basis, 65-75% of SiO.sub.2, 0-5% of Al.sub.2 O.sub.3, 5-15% of CaO, 0-10% of MgO, 10-18% of Na.sub.2 O, 0-5% of K.sub.2 O, 0.0005-0.02% of Cr.sub.2 O.sub.3, 0.0010-0.01% of CoO, 0.0001-0.03% of Se and 0.1-0.19% of Fe.sub.2 O.sub.3 with provisos that the total of CaO and MgO is from 0 to 16% and that the total of Na.sub.2 O and K.sub.2 O is from 10 to 20%. However, this glass is insufficient in absorption of infrared and ultraviolet radiation, and thus is not useful for vehicle windows.
JP-B-58-13504 shows a bronze-colored ultraviolet absorbing soda-lime-silica glass containing, on a weight basis, 0.2-0.5% of total iron expressed as Fe.sub.2 O.sub.3, 5-25 ppm of Se and 0-20 ppm of CoO. The optical characteristics of this glass at a thickness of 3 mm with using standard illuminant C are as follows.
Visible light transmittance Y is not less than 70%. Light transmittance in the wavelengths of ultraviolet rays is smaller than that in the wavelengths of visible light rays. The excitation purity Pe is from 2 to 6%. The dominant wavelength .lambda..sub.D is from 570 to 580 nm. However, this glass is still insufficient in ultraviolet radiation absorption.
JP-B-63-44695 shows a bronze-colored ultraviolet absorbing soda-lime-silica glass containing as essential components, on a weight basis, 65-75% of SiO.sub.2, 0.3-5% of Al.sub.2 O.sub.3, 5-15% of CaO, 1-10% of MgO, 10-18% of Na.sub.2 O, 0-5% of K.sub.2 O, 0.22-2% of Fe.sub.2 O.sub.3, 0-0.01% of CoO, 0.1-0.003% of NiO and 0.0005-0.015% of Se with provisos that the total of CaO and MgO is from 6 to 16%, that the total of Na.sub.2 O and K.sub.2 O is from 10 to 20% and that the weight ratio of Fe.sub.2 O.sub.3 to CoO is not less than 100. This glass exhibits a dominant wavelength of 580 to 590 nm by the 2.degree. visual field measurement with using standard illuminant A. However, this glass may change in color and may become weak in strength in heat treatment due to the addition of NiO.
U.S. Pat. No. 2,444,976 shows a ultraviolet absorbing glass having a golden tint, which contains, on a weight basis, 65.6% of SiO.sub.2, 0.4% of the total of Al.sub.2 O.sub.3 and Fe.sub.2 O.sub.3, 11.8% of CaO, 12.2% of Na.sub.2 O, 0.5% of As.sub.2 O.sub.3, 7.5% of TiO.sub.2 and 2.0% of CeO.sub.2. However, this glass is insufficient in infrared absorption.